Pharmaceutical preparation which, after administration, enter into the citric acid cycle upon their biological degradation or belong thereto are gaining greater and greater importance in therapy, generally in high dose, since it is possible by the use thereof to mitigate or cure cryptogenically caused diseases. Thus, fumaric acid impedes the growth of the Ehrlich ascitic tumor in mice, reduces the toxic effects of mitomycin C and aflatoxin (Kuroda, K. M. Akao, Biochem. Pharmacol. 29, 2839-2844, 1980/Gann. 72, 777-782, 1981/Cancer Res. 36. 1900-1903, 1976) and possesses an antipsoriatic as well as antimicrobial action (C. N. Huhtsnen, J. Food Sci., 48, 1574 (1983), M. N. Islam, U.S., Pat 4 346 118-of August 24, 1982/C.A., 97, 161317b (1982)).
High doses of administration of fumaric acid, its salts or its previously known derivatives such as dihydroxy fumaric acid, fumaramide and fumaronitrile have, upon parenteral, dermal and particularly peroral administration such an unacceptable rate of side effects and high toxicity (P. Holland, R. G. White, Brit. J. Dermatol. 85, 259-263, 1971), that it has heretofore been necessary generally to refrain from such therapy.